1. Field of the Invention
The present invention relates generally to a display panel filter, and more particularly to a filter having particular application for use with a plasma display panel. The present invention also relates to a method of making such a filter.
2. Description of the Prior Art
Visual display panels commonly known as plasma display panels or flat panel displays have been recently introduced for the purpose of displaying visual images or information on relatively large, flat screens. Plasma display panel technology utilizes selectively energized inert gas ions to bombard phosphors on a display screen, similar to an electron beam bombarding phosphors on a cathode ray tube (CRT) screen. Plasma display panels are similar to CRT displays in that both provide a means for visually displaying information or images from an input signal; however, important differences exist. First, a CRT display requires a significant depth dimension relative to the size of its display screen to accommodate a generally funnel shaped rearward portion for generation and deflection of the electron beam. Second, most CRT screens are curved. In contrast, the energization of the ions in a display panel using plasma display technology occurs in a relatively thin vacuum chamber adjacent to the display screen, resulting in a relatively thin display panel with a flat view face. Thus, plasma display panels are currently used primarily for relatively large display panels where CRTs are impractical or where a display panel with a significantly reduced depth dimension is necessary or desirable.
Although plasma display panels provide significant advantages and improvements by facilitating relatively large visual displays with a reduced panel depth and by otherwise facilitating the use of displays in environments with space restrictions which preclude the use of conventional CRT displays, new problems have arisen. These problems relate to the quality of the visual display, increased infrared (IR) and electromagnetic interference (EMI) emissions, low contrast ratio and consumer safety issues. For example, photopic reflection from current plasma display panels is in excess of 15%. This adversely affects the quality of the display. Further, operation of the plasma display panel produces or has the potential of producing infrared (IR) emissions which are capable in some cases of interfering with a remote control of the panel or other devices utilizing infrared signaling. Still further, operation of the plasma display panel results in the generation and emission of electromagnetic interference (EMI). Accordingly, many plasma panel displays fail to meet governmental TCO and FCC requirements for EMI emissions and the stricter standards for various military, aircraft and other uses. The above problems necessary limit the applicability and desirability of using plasma display panels.
Accordingly, there is a critical need in the art for a device or a filter useable in conjunction with plasma display panels for addressing and solving the above problems and limitations. A need also exists for a method of making such a device or filter.
To satisfy the need in the art, the present invention provides a device in the form of a single filter which is useable in conjunction with plasma display panels and which functions to reduce reflection after assembly to acceptable levels, to increase contrast enhancement, to assist in reducing EMI emissions to levels which comply not only with consumer safety regulations, but with the stricter military and aircraft standards, and to reduce infrared emissions in the 800 nm-1000 nm range to a level which does not interfere with remote control operation.
Generally, the present invention comprises a transparent filter lamination including a pair of outer substrates and one or more conductive layers and one or more dielectric layers laminated between the substrates. The combination of the conductive and dielectric layers function to provide the desired EMI and IR shielding and assists in reducing reflection and increasing contrast enhancement. The present invention contemplates that this combination of layers may be provided as a single film containing both conductive and dielectric layers or a structure in which the conductive and dielectric layers are applied and laminated separately.
More specifically, the preferred embodiment of the present invention comprises a transparent filter lamination including a pair of transparent substrates, an anti-reflective coating applied to the outer surfaces of each of the transparent substrates and an EMI/IR shielding film or filter laminated between the substrates. This shielding film or filter may be a single film comprised of a plurality of conductive and dielectric layers or it can be a conductive layer and a separate IR shielding layer or dielectric. The filter further includes an electrical connection member electrically connected to conductive layers within the EMI/IR shielding film. A means is also provided in the form of an electrical wire or the like for electrically connecting the electrical connection member to a grounded terminal.
In the preferred embodiment, the transparent substrates comprise view side and panel side substrates with the view side substrate being the substrate further from the display screen and the panel side substrate being the substrate closest to, or adjacent to, the display screen. Similarly, each of the substrates includes a view side facing away from the display screen and a panel side facing the display screen. In the preferred embodiment, the EMI/IR shielding film or filter is applied directly to the view side of the panel side substrate and the two substrates are laminated together by a urethane or other adhesive. The preferred embodiment further includes an environmental degradation barrier for the conductive layers within the EMI/IR shielding layer. This barrier extends around the edge of the laminated filter and is constructed of a conductive material. This barrier is electrically connected both with the electrical connection member or busbar and with a grounding terminal.
The method aspect of the present invention relates to a method of making a filter of the type described above for use in conjunction with a plasma display panel. Such method generally includes providing first and second transparent substrates, applying an anti-reflective coating to each of these substrates by sputtering, applying the EMI/IR shielding film or filter to one of the substrates and then laminating the substrates to one another.
Accordingly, an object of present invention is to provide a filter for use in conjunction with a plasma display panel.
Another object of the present invention is to provide a plasma display panel filter which provides anti-reflective, EMI shielding, contrast enhancement and infrared shielding capabilities and which also complies with consumer safety requirements.
A further object of the present invention is to provide a plasma display panel filter having one or more conductive layers and one or more dielectric layers formed or laminated between a pair of outer transparent.
A still further object of the present invention is to provide a plasma display panel filter with an improved film providing both EMI and IR shielding capabilities.
A further object of the present invention is to provide a plasma display panel filter with an improved means for electrically connecting the EMI shielding layer to a grounding terminal.
A still further object of the present invention is to provide a plasma display panel flter with an electrically conductive material around the edge of the filter to prevent environmental degradation of the EMI shielding layer and to maximize the EMI shielding efficiency of such layer.
Another object of the present invention is to provide a method of making a plasma display panel filter of the type described above.
These and other objects of the present invention will become apparent with reference to the drawings, the description of the preferred embodiment and method and the appended claims.